hi guys,
well my 1991 vette with the 8 t/b runner intake and haltech stand along computer is still up at the tuners getting fixed!!
the tuner guy had the vette finally running but just before the vette was to be put on the dyno for fine tuning and then the engine just cut out and stopped and couldnt get it started again.
the guy thought it was out of fuel because
as it showed empty but guage doesnt work properely i told him.
so it might of had some fuel or not but the fuel that i put in it about 3-4 months ago.
so the fuel could be stail.
so he put some more fresh fuel in.

he is saying that now he is getting all signals properely and it pumps up fuel but then just dies.
it is set at 30 psi as it is running 30 psi fms injectors.
injectors have been serviced and cleaned also!!
it has a new aeromtotive regulator and ,new hp fuel pump and sock,new fuel filter also.
so what could this be do you reackon please ??
would it have some thing to do with the oil preasure sensor switch.
any other ideas to look for guys??
thanks
glen

that rail pressure seems awful low, if theyre 30lb injectors, you need to find out at what rail pressure they flow 30lb

stock LT4 injectors flow 26.4lb on a 43psi rail, on a 30psi rail they would only flow about 18lb, not enough for the car to run on.

Thats where I would start

hi rich,
thanks for the reply mate!!
ok mate,i will let the guy know!!!
but the car was running and idleing ok before the tuner said so i dont know whats gone wrong now!!
so may be would bump up the f/p to 40 psi ??
thanks
glen

no problem

That could be it, I would contact the injector manufacturer to see what they flow at what PSI.

Like I said they may be 30lb injectors, and he may have tuned the computer at a 30lb constant, but if the input pressure is low, then they wont be flowing 30lb, so the tune would be off as well.

Just gotta figure out what rail pressure those injectors flow 30 at, and then set the reg and see what happens.

ok mate,good point and helpful info!!
i will discuss this with the tuner tomorrow about what you just mentioned.
cheers man
glen

Sorry, I don't remember exactly what's being done on the car. Is the motor stock? Are the injectors original? Do you have an adjustable FPR (that's what it sounds like?). On my 89, which should be same as 91, the fuel pressure when the key is on (after the fuel pump primes the system) is around 42-43 psi (per the FSM, it should read between 40.5-47). That's stock, though, so if there are changes it could be different.

Matthew

Oil pressure switch has nothing to do with it. It isn't capable of shutting off the fuel supply unless your fuel pump relay fails and your oil pressure drops to nothing.

The fuel pump relay is used to prime the system, so it sounds like that part is working.

The engine should be able to start and run a few seconds off the primed fuel alone. Is it doing that?

Quote:

hi guys,
well the motor has standard cam and heads but with long 1/3/4" headers, 2.5 " mandrel pipes true dual pipes,x-pipe,high flow cats,magnaflow rear mufflers aeromtotive adjustble fuel regulator,30 lb fms injectors,8 x 50 mm diameter throttle body indvidual cross ram intake manifold and haltech stand alone computer,msd dist and coil,underdrive pulley kit,polltion pump delete,180 degree stat,low temp fan switch,uni filter sock filters,
any way i metioned what rich said about the fuel rail preasure but the tuner said it is not a problem.
you turn on the key and it primes and pumps up fuel ok but when you go to start it he said it is not getting enough fuel!!
so im not sure what the hell is going wrong with it now!!

im leaving this shit standard engine in until i can be sure the new haltch computer is wired up rite and working properely before i fit in my new 388 c.i all forged /light weight stroker full modded race engine.
cheers
glen

Quote:

You need to monitor the fuel pressure while it's running. If that's the case, it sounds like a fuel delivery issue - clogged fuel filter or bad pump, possibly. I'd check that FPR, too, some of those adjustable ones have been known to be bad.

Matthew

hi matt,
thanks for the reply.
i for got to mention,it has new fuel filter,new hp fuel pump and new regualtor all only 6 months old with hardly any use at all!!
cheers
glen